1. Field of the Invention
This invention relates to an improved dispenser for a stack of sheet material, permitting the dispensing of one sheet at a time from a stack of sheets throughout the stack with the next successive sheet being disposed for easy grasp. In one aspect the invention relates to an improved dispenser for adhesively joined sheets which will permit dispensing sheets serially from a stack without the next to be dispensed sheet falling back into the cartridge upon separation therefrom of the dispensed sheet.
2. Description of the Prior Art
This invention is directed to an improvement in dispensers for dispensing individual sheets from a stack of sheets releasably joined together and disposed within a cartridge from which they are to be dispensed.
U.S. Pat. No. 4,416,392, issued Nov. 22, 1983, to Daniel D. Smith, and assigned to the assignee of this application, is directed to a dispenser for sheets stacked together in a manner similar to the stack of sheets for use with the present invention. In the Smith patent a dispenser is shown which is in the form of a shallow box from which sheets may be dispensed individually. The number of sheets which may be dispensed from a box is limited to a stack having a height not significantly greater than three-fourths the length of a sheet such that the sheets being dispensed, when they near the bottom of the stack, will not fall back into the cartridge when separated from the sheet being dispensed. A second embodiment disclosed in the Smith patent is a dispenser wherein the stack of sheet material was urged towards the dispensing opening such that the sheets were generally maintained in the same position adjacent the opening until the last of the sheets in the stack were dispensed.
The dispenser of the present invention is unique in that it provides, in a rather uncomplicated and inexpensive manner, a guaranteed positioning of the next sheet to be dispensed in the dispensing opening without regard, necessarily, to the numbers of sheets in the stack placed in the cartridge.
The idea of providing a "pop-up" dispenser for dispensing sheets of notepaper is very desirable and, as is often the case, it is desirable to be able to grab a sheet of notepaper from the stack when only one hand is available to grasp the sheet and to separate it from the stack. With sheets which are in tablet form, wherein the sheets are bonded together by a gum adhesive at one edge or are to be separated along a perforation from the other sheets in the tablet, such as dispensing procedure with one hand is impractical, if not impossible. The dispensing of sheets of notepaper individually with one hand is possible when the sheets are placed in a pad such that the sheets are adhered together along alternately opposite edges by a peelable medium. One such medium is a narrow band of a repositionable acrylate copolymer microsphere-structured pressure-sensitive adhesive, such as that described in U.S. Pat. No. 3,691,140, assigned to the assignee of this application.
While both of the dispensers disclosed in the Smith patent, U.S. Pat. No. 4,416,392, function excellently for their intended use, the dispenser with the fixed opening and resembling a box to contain the sheets, is limited in the number of sheets which can be dispensed from a pad before experiencing unwanted multi-sheet dispensing and the sheet fall back. This multi-sheet dispensing is the result of a decrease in the amount of dispensing resistance applied to the pad by the exit opening as the pad is consumed. This problem becomes more severe as the height of the pad increases since a point is reached where the sheets do not need to buckle but merely to bend to allow the edges of the sheets which are joined to be drawn through the exit opening. For example, if the stack of sheets have a cube format where the pad height may exceed the sheet length, a fixed exit opening is not practical.
A second problem which is prevalent with the fixed exit opening design is that no means is provided to prevent the top sheet of the pad from falling back through the exit opening as the sheets are being dispensed. When this problem occurs the user is required to fish the end of the pad back through the exit opening, thus defeating the object of the dispenser. This problem also increases in severity as the pad height increases.
The dispenser construction that utilizes the spring elevated base which moves the stack of sheets progressively toward the opening as the sheets are dispensed off the top of the stack requires a number of parts, i.e. a base, a spring, a platform upon which to stack the sheets, and a containment housing having the opening through which the sheets are dispensed.
The present invention overcomes the problems associated with the dispensers of the earlier Smith patent by (1) providing an exit opening which is movable and self-adjusts to compensate for the varying resistance requirements encountered during the dispensing of individual sheets from the pad; and (2) providing a means to grip the sheets, thus preventing the falling back of the sheets through the exit opening. This performance improvement is accomplished without the need for a mechanical device within the dispenser.